The invention relates to a chair having at least one foot and a support profile, on which a seat and, if appropriate, a backrest is arranged, it being possible for the seat to be adjusted in a stepless manner in height on the support profile and to be fixed in a secured manner at a desired height by a height-securing means, a connecting element being provided between the support profile and seat, and the seat being mounted in an articulated manner in relation to the connecting element.
Chairs are available in a wide variety of different shapes and forms. The present invention is concerned specifically with a chair for which it is possible to set the seat height and/or seat depth. The invention is also concerned with a chair which is collapsible.
U.S. Pat. No. 4,148,523, for example, discloses a chair of which the seat can be adjusted in height along a support profile. For adjustment purposes, the seat is raised, a connecting element is displaced along the support profile and the seat is then lowered again, in which case it subjects the support profile to a clamping action.
This chair has the disadvantage that if, for example, the seat is raised accidentally, the height is easily adjusted of its own accord. The clamping action of the seat in relation to the support profile depends essentially on the pressure to which the seat is subjected.
In order to avoid accidental displacement of the seat height, height-securing means are provided on the seat. It is likewise the case that such height-securing means are known and commonly used in a wide variety of different shapes and forms.
For example, EP 1 020 138 A1 describes a seat in which height and depth adjustment takes place by means of a toothed engagement strip, which runs on a chair framework, and a retaining device, which is assigned to the seat and on which a gearwheel, which meshes with the toothed engagement strip, is seated and drive means, which can be driven in rotation by the gearwheel, are arranged.
In order for it to be possible, then, to fix the seat at a certain height, the retaining device is assigned a clamping device, which clamps the retaining device firmly on the chair framework.
A further height-securing means is described in DE 195 19 739 A1. Here, a seat is connected to a support element via a screw and via a supporting arm. The supporting arm engages in a slot in the support element and, following release of a fastening means, can be displaced vertically in order then to be fixed again by means of the fastening means.
WO 99/00038 describes a further chair, which likewise has a height-adjustable and depth-adjustable seat panel which is assigned a support element. A height-securing means is produced here by the interengagement of noses on the support element with grooves in guide rails in side elements of the chair and of the support element itself with grooves of a gearwheel-like element on the rear side of the chair, clamping elements ensuring that the seat is fixed.
U.S. Pat. No. 6,017,089 discloses a chair of the above-mentioned type, the seat of which has a frame which is assigned a clamping device. This clamping device comprises frictional elements, which are assigned to the frame of the seat via pins. When the seat frame is rotated in the direction of a horizontal position, the frictional elements come into frictional contact between the support profiles of the chair, as a result of which a clamping action is produced. This clamping action is secured by a push-in pin.
The disadvantage with the above-described height-securing means, however, is that they are mostly connected directly to the seat or else to the support profile of the seat. This gives rise to a complicated construction for the height-adjusting means and thus also for the height-securing means, which results, in turn, in more difficult handling.
Furthermore, in the case of some of the above-mentioned height-securing means, the action of securing the seat at the desired height is insufficient since they rely merely on a clamping action between the seat and support profile. Furthermore, the height-securing means do not operate automatically.
Added to this is the fact that, in particular if use is made of, for example, screw-like elements, the screw-like element may jam in the support profile or the like, which may result, inter alia, in possible injury to the user.
The object of the present invention is thus to develop a chair of the above-mentioned type which is provided with a height-securing means which is highly variable in terms both of its settings and its handling, is easy to operate and, nevertheless, provides a sufficient securing action against the seat being adjusted out of its desired height.